Blogs

MicroGear hardware in the loop demonstration with FlightGear

Posted by Curt Olson on December 2, 2009 at 1:30pm
I'm almost embarrassed to post this video. It was done almost entirely with open-source software, so it's obviously way behind what people are doing with commercial software and commercial systems. But I have fun and entertain myself with this stuff, so I thought I'd share a brief snippet.

https://www.youtube.com/watch?v=yIDQq93cpcoWhat you are seeing is FlightGear (http://www.flightgear.org). I have a FlightGear model of a Sig Rascal 110 (which I've flown in real life many times.) The 3d model and the flight dynamics model are also open-source so of course are also subpar from anything that would be done commercially. The FlightGear flight dynamics engine is outputting gyro, accelerometer, and gps data to an external embedded computer running MicoGear. MicroGear takes the "sensor" data, runs it through a 15 state kalman filter (the one piece here that isn't open-source) and estimates roll, pitch, yaw, and location.Because this is FlightGear I already know the true pitch, roll, and yaw, but I promise I'm not cheating here. The kalman filter on the embedded board is estimating these values and using them as input to the autopilot and routing algorithms also running on the embedded board. The only difference between this and real life from the microgear/embedded-processor point of view is that it's not getting it's data from the onboard sensors and it's not driving servos directly. Instead it sends the servo commands back to FlightGear and the control surfaces are moved over there in the simulator.This turns out to be a really nice hardware in the loop testing platform and many subtle issues that show up in real life, also show up in the simulator. Because this is FlightGear, a person can throw a variety of weather conditions at the system, turbulence, high winds, etc. You can disable fuel consumption and run for hours or days if you like.I am very tempted to turn in a "virtual" entry into one of the upcoming DIY drones contests. :-) Oops, I almost started to crack a smile there. Ok, I'm back to my long, sullen, down trodden facial expression, because after all this is all pretty much all open-source software -- which just sucks -- total crap I know -- sorry to even waste your time and bandwidth with any of this guys. I won't post anything ever again until I have something actually useful or interesting to show.Curt.
E-mail me when people leave their comments –
Follow

You need to be a member of diydrones to add comments!

Join diydrones

Comments

  • Maryam Awan January 26, 2011 at 9:45pm

    Hi Curt,

    Sorry to bother you again but is it possible for you to send me the link or exe file for FlightGear v1.9.0?

    Thanks.

     

    Regards,

    Maryam

  • Curt Olson January 25, 2011 at 8:45pm
    Hi Maryam,

    Sorry for misunderstanding your question. Unfortunately I've never played around with the APM and haven't had any involvement in their documentation or wiki, so I really don't have any advice to offer with that. Hopefully someone closer to the APM can jump in and help here. Maybe there's contact info on the wiki for someone you could ask?

    Regards,

    Curt.
  • Maryam Awan January 25, 2011 at 8:28pm
    Thanks for your reply but I don't think I was able to convey my problem properly. Actually I'm using FlightGear simulator too. There is a step by step guide for hardware-in-the-loop simulation with FlightGear on the following link:
    http://code.google.com/p/ardupilot-mega/wiki/FlightGear

    But one of the steps listed there is:
    "Make sure the ardupilot is setup to output for Xplanes".
    I don't understand what this means. Can you please explain?

    Also for hardware I have ArduPilot Mega. Any advice regarding that?

    Thank you. I really appreciate your time.

    Regards,
    Maryam
  • Curt Olson January 25, 2011 at 6:07am

    Hi Maryam,

    You might be mixing up a couple different things here.  The simulator I used for my demonstration is FlightGear (www.flightgear.org).  Anything you see about XPlane comes from a different project, and I don't know anything about that.

    We did discover an issue with the flightgear launcher where it would reserve too much memory for many systems to handle and could cause everything to grind to a halt.  We've addressed that problem in our development tree and it should be fixed for the next release.

    For the hardware in the loop demo, I was using a bread board prototype of a new autopilot board I'm involved with developing.  I flew the crap out of the prototype all last summer and into the fall.  Now hopefully in a few weeks we'll get some actual boards.  I'm not big into hyping stuff, and it's not ready to go yet (and this stuff always takes *longer* than planned), but it will be a very solid performer and I think it will have some interesting features and capabilities I hope to be able to demonstrate pretty soon.

     

    Regards,

     

    Curt.

  • Maryam Awan January 25, 2011 at 5:53am

    hi

    I have a problem with which I hope you can help me. Firstly I wanted to ask what it means by "Make sure the ardupilot is setup to output for Xplanes" in FlightGear aharware-in-the-loop setup? Does it mean I have to follow the APM steps as in for Xplane? Kindly explain.

    Secondly I'm using Windows XP so is there any limitation on RAM? I'm getting the OpenGL related problem because of which the simulation doesn't even start and gets stuck? What could I be doing wrong?

     

  • Héctor García de Marina May 22, 2010 at 12:35am
    The best way to model a motor is to know about the motor itself.

    I mean, you have to be able to measure rpm, temperature, V / I curves. And of course, you have to model the battery as well with temperature, discharge rate etc
  • Curt Olson May 21, 2010 at 8:25am
    I was just suggesting that you download the model and investigate yourself. You will have to do this anyway if you are interested in adapting elements of the Rascal to your model.

    Best regards,

    Curt.
  • tejeshwi May 21, 2010 at 8:21am
    Hi Curt,

    But what kind of engine does your model use? i need to model and electric engine Funjet. Is it possible to use your model for an electric engine?

    Cheers,
    Tejeshwi
  • Curt Olson May 21, 2010 at 8:13am
    The Rascal model that I have made is part of the standard FlgihtGear distribution, so you can find it on the aircraft download page at www.flightgear.org ... you are welcome to browse through the different configurations and as long as you abide by the open-source terms, borrow any pieces from it that you like. Do you have a 3d model of the funjet? If you end up with a decent simulated version, it would be great to roll this back into the FlightGear project, I'm sure others would be interested.
  • tejeshwi May 21, 2010 at 8:05am
    You can reach me at tejeshwi007@gmail.com. I hope ypu shall oblige me by doing the necessary.

    cheers,
    tejeshwi
This reply was deleted.